Drive Unit for Extracting Water, Petroleum or Other Fluids

ABSTRACT

This invention is a type of pump drive unit for extracting water, petroleum or other fluids by alternating between top-down and bottom-up operation using a pumping string that enables fluids to be extracted from thousands of meters down. This unit can be used in any well that uses a mechanical pump without any modification to the existing installation, and it achieves a reduction in operating and extraction equipment costs on the order of 20%. The drive unit has a piston ( 2 ) that is able to slide inside the vertical hydraulic cylinder ( 4 ) upon adding a drive fluid, where the piston rod ( 2 ) is the polished rod of the sucker rod string ( 1 ).

TECHNICAL FIELD

This invention consists of a pump drive unit for extracting water, petroleum or other fluids which alternates between an up and down movement using a pumping string that enables fluids to be extracted from thousands of meters down. This unit can be used in any well operated by a mechanical pump without the need to modify the existing facility, with a reduction in operating and extraction equipment costs of around 20%.

STATE OF THE ART AND PROBLEMS TO BE SOLVED

With regard to state of the art, we know that mechanical pumping currently is used in two thirds of the extraction wells worldwide, and that in Argentina alone, this technology is used to operate approximately 70% of the wells. The growing demand for energy creates the need to optimize pumping facilities in order to bring industry costs on a par with international values.

For this reason, one of the objectives of this invention is to reduce operating costs as well as ensure environmental safety and care when pumping fluids.

Operational flexibility of the drive unit proposed herein is obviously necessary in any well requiring mechanical pumping and, above all, in those wells, which due to their stimulation system, need to use pumping units able to offer a wide range of speeds.

The drive unit is tasked with raising the sucker rod string and storing potential pneumatic energy by offering the ability to work at very low cycles per minute and thus allow the pump to be filled completely with a lower dynamic load.

The pumping achieved with this invention reduces the structural load on the equipment and increases the useful life of the sump floor, since the pump sucker rod string works at a constant load.

In a state-of-the-art drive unit, a piston traveling the length of a vertical cylinder is used. However, in that unit the piston has its own drive shaft and has to be connected to the sucker rod string on each side of it to be independent of the rod strings or it is either inserted inside the piping or a good distance from the wellhead along a length equal to the stroke, so that when the piston is at its maximum raised position, one can imagine the rod protruding from the end of the cylinder by a length equal to the piston stroke. This makes for either a very unstable structure many meters tall that is too high to be stable or else one that is difficult to regulate.

On the other hand, this invention proposes that the polished piston rod of the sucker rod string be the rod of said piston, which results in an extremely simple drive unit comprising a cylinder with inner piston fastened to the previously mentioned polished rod of the sucker rod string, as now there is no rod to be removed from this cylinder thereby augmenting the drive unit structure and increasing the need for more structural fasteners.

This invention optimizes the balancing of the weight of the sucker rod string, which makes for the achievement of high rod pull capacities, a wide and varied range of speed and stroke length, and due to its configuration, it allows for independent control of the speed of the upward and downward action of said sucker rod string, as well as load control.

In addition, it offers a substantial reduction in weight and volume, thereby facilitating installation and transportation, with a consequent reduction in logistical costs, since the unit can be delivered completely assembled, which means that it can be installed with just one hydro crane. Its size can also be adapted to each particular operation, something that is not possible with any other drive unit in existence today.

Another essential point is that the operating parameters, such as speed and maximum load, and therefore the level of well operation, acceleration, and brand investment point, can be adjusted without needing to stop the equipment. Moreover, the use of a drive unit such as the one proposed herein dispenses with the need to use variable speed drives.

This therefore offers a much more efficient pump drive unit since it only consumes energy in order to raise the fluid column and since it is operating with a constant well level and taking advantage of the output of same to the maximum extent.

On the other hand, since there is no stuffing box, there is no risk of fluid spills and regarding any safety or operating risks, there are no exposed moving parts, which eliminates any chance of personal injuries.

BRIEF DESCRIPTION OF THE FIGURES

In order to make the subject matter of this invention more intelligible, it has been illustrated, as one of the preferred ways, using schematic figures, and the schematics are used as examples for demonstration purposes, where:

FIG. 1 is a schematic cross-section of the basic components of a pump drive unit for extracting water, petroleum or other fluids using this invention;

FIG. 2 shows a side view of the pump drive unit we have invented with the tanks shown lengthwise around the central cylinder of this unit, and a lower partial cross-section;

FIG. 3 shows a detail view of “A” in FIG. 2;

FIG. 4 is cross-section view of the polished rod in the drive unit which incorporates a separator on its threaded end.

The same reference numbers and letters used in all the figures match up with identical components of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a pump drive unit for extracting fluids from a well, with the polished rod of the sucker rod string 1 operated alternately by this unit, so that it moves the extraction pump located in the depths of the well. The drive unit has a piston 2, which is coupled to the polished shaft of the sucker rod string 1, and piston 2 is driven by the pressure of the incoming fluid entering through the piping 3, so that it is able to move up and down the whole length of the stationary vertical hydraulic cylinder 4. As can be observed, the movement of this piston 2 will pull sucker rod 1, which has been connected to the pumping rod, thereby producing the upward and downward motion of the extraction pump.

The use of the polished rod of sucker rod string 1 with the function of the rod on piston 2 will enable the height of the drive unit to be identical to the maximum stroke of the unit, unlike other state-of-the-art hydraulic drive units in which the piston rod is one more component of the drive unit and, in addition, when piston 2 is at its highest, it protrudes from the hydraulic cylinder 4, regardless of whether it is going up or down.

FIG. 2 presents a preferential embodiment of the drive unit in which six tanks 5 containing a compensating fluid such as nitrogen, which is used for the system controlling the movement of piston 1, are spaced around hydraulic cylinder 4. These provide greater stability to the hydraulic cylinder 4.

FIG. 3 allows us to see a preferential form of connecting the polished rod of the sucker rod string 1 to piston 2 of the pump drive unit that is the subject matter of this invention. This coupling includes two flanges, an upper one 6 or the hydraulic cylinder flange 4 supported in a seat 7 a of lower flange 7 or flange connected to the well and fastened by bolts inserted into threaded cavities 8.

To drive piston 2, fluid will be inserted into chamber 9, which will force piston 2 to rise or fall based on the pressure in the chamber 9.

FIG. 3 shows the seal assembly with its body 11 threaded into the polished rod of the sucker rod string 1 and supported in a seat 21 in the lower flange 7, within which the following are included: a guide ring 12 in contact with the piston 2, underneath this guide ring is a housing 13 with a first hydraulic seal, and a contiguous guide bushing 14, and under the guide bushing is a cavity 15 comprising the second stage of the hydraulic seal. Underneath this second-stage seal is a third-stage hydraulic seal 16 on the seal assembly body 11, able to separate the hydraulic fluid from the extraction fluid, in which the cleaning components 22 (“wipers”) of the polished rod of the sucker rods string 1 are also located; these keep dirt from reaching the rest of the seal assembly body components 11. Schematically at the end of the polished rod of sucker rod string 1 is a body that acts as a piston stop 2.

FIG. 4 shows the function of a spacer 18 that is located above the piston 2, by inserting it in the polished rod of the sucker rod string 1; it is fastened, thanks to a threaded coupling 19 on the end of the polished rod of the sucker rod string 1. Therefore, the desired spacing in the pumping unit is achieved by adding separators 18 between the piston 2 and the coupling 19 on polished rod 1. The hydraulic seals also shown in FIGS. 3 and 4 shall preferably be “PolyPak” seals, as they are known in the technical field.

Possible drive fluids for use in this drive unit can be, in our opinion, any of the fluids used in the industry to facilitate piston movement. 

Having described and specified the nature and scope of the invention and how it works in practice, we would claim the following as our exclusive right and property:
 1. Pump drive unit for extracting water, petroleum or other fluids, capable of producing alternating upward and downward movement in a pumping unit using a sucker rod string (a), the drive unit being the type of unit that has a piston (2), able to slide inside a vertical hydraulic cylinder (4) upon adding an operating fluid characterized hi that the piston rod (2) is the polished rod of the sucker rod string (1).
 2. Pump drive unit for extracting water, petroleum or other fluids, according to patent claim 1, characterized in that the coupling of said piston (2) to said polished rod (1) of the pump string (1) consists of a lower flange (7) for connection to the well with a seat (7 a) in which the upper flange (6) of the hydraulic cylinder (4) rests; and on which the upper flange (7) has a rim (20) for supporting said hydraulic cylinder (4); with a seal assembly that sits in said lower flange (7) and is threaded into the polished rod (1) of the sucker rod string.
 3. Pump drive unit for extracting water, petroleum or other fluids, according to patent claim 2, characterized in that the seal assembly consists of a body (11) on which the guide ring (12) is housed above it and makes contact with the piston (2); underneath this guide ring is a housing (13) with a first hydraulic seal and contiguously a guide bushing (14); a cavity (15) can be seen below said guide bushing which forms a second-stage hydraulic seal and under this second-stage seal is the body (11) of the seal assembly, a third-stage hydraulic seal (16), capable of separating the hydraulic fluid from the extraction fluid, in which the cleaning components or “wipers” (22) of the polished rod (1) of the string of sucker rods are also located.
 4. Pump drive unit for extracting water, petroleum or other fluids according to patent claim 1, characterized in that on the end of the polished rod (1) of the sucker rod string and above the piston (2) is at least one spacer (18) fastened by a coupling (19) threaded into said end of the polished rod (1) of the sucker rod string. 